1. Field of the Invention
The present invention generally relates to fluid level sensing. More particularly, the present invention relates to a method and an apparatus for sensing the level of fluid in a reservoir which incorporate a pair of pivotally mounted floats. In one particular application, the present invention relates to a method and apparatus for sensing the level of fuel within a gas tank of a motor vehicle.
2. Discussion
In automotive fuel tanks, it is common practice to utilize a fuel pick-up device with or without an intake fuel pump and also supporting a fuel level indicating mechanism. The fuel indicating mechanism typically has an elongated rod with a free end supporting a float which moves along with changes in fuel levels. The other end of the rod is pivotally mounted to an indicating or sensor mechanism. The indicating mechanism typically includes an elongated electrical resistance grid and a contact pad which moves with movements of the float and rod as the fuel level changes. The movement of the contact pad along the resistance grid changes electrical characteristics of a circuit, thus providing a variable input to a fuel indicator gauge located within the passenger compartment of the associated vehicle.
The aforedescribed fuel indicators or sensors within the fuel tank are generally known. An example of such an indicator is found in commonly assigned U.S. Pat. No. 4,841,771 which is hereby incorporated by reference as if fully set forth herein. In this patent, a level sensing device includes a single float member which follows liquid fuel changes in the tank. The float member is attached to a free end of a float rod. A molded crank arm member is operably connected to the float rod. The crank arm supports a metal contact carrying member which has an elongated arm extending therefrom. Rotation of the rod produces corresponding rotation of the crank arm. Resultantly, arm and the contact pad are moved along a surface on an arcuately shaped resistor board.
While known fuel indicators or sensors have proven to operate satisfactorily for their intended purposes, they are all associated with limitations. For example, many known indicators or sensors may occasionally reflect a fuel level which is not completely accurate due to certain operating conditions. Such operating conditions which may effect the accuracy of known indicators or sensors include vehicle parking or operation on inclined surfaces and sloshing of fuel during vehicle operation. A need remains in the art for more accurately determining the level of fluid in a container, such as a fuel tank, throughout a range of motor vehicle operations.
It is a general object of the present invention to provide a method and an apparatus for more accurately sensing a level of fuel within a fluid receptacle.
In one form, the present invention provides an apparatus for sensing a level of fluid within a container. The apparatus includes a support coupled to the container. The apparatus additionally includes first and second floats. Each of the first and second floats is pivotally coupled to the support proximate a first end. The apparatus further includes a position sensing mechanism for sensing the relative positions of the first and second floats and responsively determining the level of fluid within the container.
In another form, the apparatus of the present invention includes a first cantilevered arm having a first float coupled to the container. The apparatus additionally includes a second cantilevered arm having a second float coupled to the first cantilevered arm. The apparatus further includes a position sensing mechanism for sensing the relative positions of the first and second cantilevered arms and responsively determining the level of fluid within the container.
In another form, the present invention provides a method for sensing the level of fluid within a container. The method includes the following general steps:
pivotably mounting a first float within the container;
pivotably mounting a second float within the container;
determining a position of the first and second floats; and
calculating the fuel level within the container as a function of the positions of the first and second floats.